1. Field of the Invention
The invention relates to a rotating electrical machine system which includes a stator having stator windings and a rotor having rotor windings, and in which the rotor is caused to rotate through control of stator current.
2. Description of Related Art
As disclosed in Japanese Patent Application Publication No. 2009-112091 (JP-A-2009-112091), there is known a rotating electrical machine in which rotor windings are provided in a rotor, and a rotating magnetic field that is generated by a stator, and that includes a spatial harmonic, gives rise to induction current in the rotor windings, and to rotor rotation torque, whereby the rotor is caused to rotate.
The rotating electrical machine requires no magnets. An efficient rotating electrical machine can be thus obtained that is comparatively inexpensive.
Other related art documents than the above Application Publication that relate to the invention include, for instance, Japanese Patent Application Publication No. 2007-185082 (JP-A-2007-185082), Japanese Patent Application Publication No. 2010-98908 (JP-A-2010-98908) and Japanese Patent Application Publication No. 2010-110079 (JP-A-2010-110079).
The temperature in the rotating electrical machine may rise depending on the operational state thereof. Such rises in temperature must be curbed.